A typical pants-type diaper has a front panel region which is intended to lie over the abdomen of a wearer, a rear panel region which is intended to lie over the buttocks of a wearer and a crotch region between the front and rear panel regions. Side panels, normally of an elasticized material, join the front and rear panels to form a continuous waist opening. Each side panel is made up of a first side panel portion adjacent the front panel and a second side panel portion adjacent the rear panel. During manufacture, the front and rear panels of a pants-type diaper precursor are folded over each other such that the first and second side panel portions overlap. Side panel seams are then formed along the laterally outermost margins of the first and second side panel portions to thereby create a closed pants-type diaper.
When forming the side panel seams, it is important that the first and second side panel portions are correctly aligned, otherwise the seams will be misplaced. Such misplacement may result in a weak product which is liable to fail in use or in an ill-fitting garment. In either case, misplaced seams are unattractive and compromise the quality of the product.
During manufacture of pants-type diapers in which the longitudinal direction of the diapers corresponds to the machine direction, the folding over of the front and rear panels means that the panel which initially is first in the machine direction has to be released from the conveyor arrangement carrying the diaper and folded over the subsequent panel which is still retained on the conveyor arrangement. As the folding is taking place, the diaper precursor is transferred to a subsequent conveyor arrangement along which the side panel seams are formed. This implies that the panel which initially is first in the machine direction is unsupported by the conveyor arrangement for a considerably longer period of time than the subsequent panel. This lack of support can lead to misalignment of the first and second side panel portions.
Problems with misplacement of the side panel seams are exacerbated when the front and/or rear panels are provided with waist elastic. During manufacture, the pants-type diaper precursor is initially temporarily secured to the conveyor arrangement in a substantially flat, laid-out condition. During folding and transfer, one or both of the panels of the diaper precursor are no longer retained on the conveyor arrangement, as a result of which the panels will contract in the cross-machine direction as the waist elastic gathers the material of the panels.
Misalignment of the first and second side panel portions has been addressed in the past by implementing corrective measures downstream of the folding step immediately prior to forming the side panel seams. Such corrective measures may include drawing out the first and second side panel portions by nipping the panel portions between an obliquely angled chain and the conveyor arrangement. It would be beneficial if it could be ensured that the first and second side panel portions are sufficiently accurately aligned without the need for extensive corrective measures.